Add Row2.contains(Row2)

[lukaseder]

A predicate similar to our existing Row2.overlaps(Row2) predicate is Row2.contains(Row2), where a row is considered a range of values, e.g.:

(1, 5) CONTAINS (2, 4) = TRUE
(1, 4) CONTAINS (2, 5) = FALSE

The implementation would look like this:

(a, b) CONTAINS (x, y)
x BETWEEN a AND b AND y BETWEEN a AND b

For the record:

(a, b) OVERLAPS (x, y)
x <= b AND y <= y

[lukaseder]

Row2 is historically special, because the SQL standard defines an OVERLAPS predicate on it. But I kinda feel that we shouldn't continue "abusing" Row2 for this purpose, but rather, introduce a new Range<T> type (possibly extending Row2<T, T>), which makes these things a bit more specific.

In PostgreSQL, this type could map to native RANGE types, too.